I did take some time and fuzzy logic but it seems to work fine on Efa4. There are other options to configure, consider this as a minimal install.
You need to create a /root/software dir and place the sophos sav-linux-free-9.tgz file in this dir.

Result:
Updating directly from Sophos.
The Free version of Sophos Anti-Virus for Linux comes with no support.
Forums are available for our free tools at http://openforum.sophos.com/
Fetching free update credentials.
Extra files updating is disabled. You can change updating settings using /opt/sophos-av/bin/savsetup.